Consumers use tissue products for a wide variety of applications. For example, various types of tissue products may be used, such as facial tissues, bath tissues, paper towels, napkins, wipes, etc. In many instances, various types of liquid-based compositions, such as softening compositions, lotions, friction reducing agents, adhesives, strength agents, etc., are also applied to one or tissue webs of the tissue product. For example, a tissue web is often softened through the application of a chemical additive (i.e., softener). However, one problem associated with some liquid-based compositions is the relative difficulty in uniformly applying the composition to the tissue web of the tissue product. Moreover, many application methods are relatively inefficient and thus may result in substantial waste of the composition being applied.
For instance, many softeners are made as an emulsion containing a particular solids content in solution. However, such liquid-based compositions are often difficult to adequately apply to a tissue web. In particular, when applying such a liquid-based composition, the tissue web can become undesirably saturated, thereby requiring the tissue web to be dried. Moreover, it is also difficult to uniformly spread the liquid-based composition on a tissue web in such a manner to provide adequate surface area coverage. In addition, some softeners contain components that cause the liquid-based composition to be formed as a solid or semi-solid. To facilitate application of these liquid-based compositions onto a tissue product, extensive heating may be required. Moreover, even after extensive heating, it may nevertheless be difficult to uniformly apply the composition to the tissue surface.
As such, a need currently exists for an improved method of applying a liquid-based composition to a tissue web.
In accordance with one embodiment of the present invention, a method is provided for a more uniform application of applying a liquid-based composition to a tissue web which may have a basis weight less than about 120 grams per square meter. The method comprises providing a papermaking furnish containing cellulosic fibers and forming a tissue web from the papermaking furnish.
In addition, the method also includes applying a foam formed from a liquid-based composition to the tissue web while the tissue web has a solids consistency equal to or less than about 100% by dry weight of the tissue web. In some embodiments, for example, the foam is applied to the tissue web while the tissue web has a solids consistency between about 60% to about 95% by dry weight of the tissue web, and more specifically, between about 80% to about 90% by dry weight of the tissue web. In other embodiments, the foam is applied to the tissue web while the tissue web has a solids consistency between about 10% to about 35% by dry weight of the tissue web, and more specifically, between about 15% to about 30% by dry weight of the tissue web.
In other embodiments, the foam is applied to the tissue web while the tissue web has a solids consistency between about 30% to about 70% by dry weight of the tissue web, more specifically, between about 35% to about 60% by dry weight of the tissue web, and most specifically, between about 40% to about 55% by dry weight of the tissue web. In some instances of the present invention, the foam is applied to a dry or over-dried tissue web having a solids consistency equal to or greater than about 95%, more specifically equal to or greater than about 97%, more specifically equal to or greater than about 98%, and more specifically equal to or greater than 99%.
The method also includes applying a foam to a wet tissue web using an extrusion head of a foam applicator wherein the extrusion head includes a flexible scraper. The flexible scraper assists in the provision of a more uniform distribution of the foam on the wet tissue web.
In other embodiments, the method also includes applying a foam to a dry tissue web using an extrusion head of a foam applicator wherein the extrusion head includes a flexible scraper. The flexible scraper assists in the provision of a more uniform distribution of the foam on the dry tissue web.
The foam may generally be applied to the tissue web in a variety of ways. For instance, in one embodiment, the foam may be drawn toward the tissue web with a vacuum slot. Further, in some embodiments, the tissue web may be supported on a first moving foraminous surface that defines a nip with a second moving foraminous surface such that the foam is applied to the tissue web at the nip.
Other features and aspects of the present invention are described in more detail below.